A torsion damper device of this kind is utilized in particular in the construction of a friction clutch, in particular for a motor vehicle, or in that of a flywheel for such a motor vehicle, then usually called a “dual mass flywheel.”
The invention is aimed more particularly at the situation in which a seat is interposed circumferentially between each of the ends of at least one of the springs, and on the other hand between one and the other of the coaxial parts, a frontal part of said seat ensuring abutment and/or centering of at least one such spring and said seat itself abutting, with a dorsal part, against one and/or the other of the coaxial parts, by being mounted pivotingly with respect to the latter around an axis parallel to their own rotation axis.
A device of this kind is described in particular in the documents FR 2 732 426 and EP-A-0 258 112.
Because they are pivotingly mounted, the seats against which the springs abut, sometimes called “cups,” allow said springs to work under good conditions during operation, even at full torque, while typically retaining a certain parallelism between their ends.
They are generally made of steel, typically of cast steel, and can optionally serve to support caps made of elastic or plastic material that, interposed in the manner of full-torque stops, advantageously allow good energy distribution within the springs before the turns of at least some of them become contiguous. They can also be constituted entirely from elastic or plastic material, and can be manufactured in particular by molding.
Lastly, they advantageously prevent centrifugation of the springs. This anti-centrifugation effect is generally of only limited effectiveness, however, since the seats themselves can be ejected from their receptacles.
The document FR 2 875 882 has furthermore already described a torsion damping device comprising seats for springs whose pivot axis is offset with respect to a dorsal face of the seat in order to improve the operation of said seat in particular in terms of the risk of ejection from the receptacles. Each seat comprises a dorsal pivot projection able to pivot in two receptacles configured in the two coaxial elements, the pivot projection being delimited in particular by a cylindrical portion having a section formed by a first circular arc whose tangents at the ends of said arc form a first acute angle. The section of the corresponding part of each receptacle is formed by a second circular arc, having the same center and radius of curvature as the first circular arc, the tangents of which at the ends of said arc form a second acute angle greater than the first acute angle. The pivot axes of the two projections are mutually parallel at a distance L between them, and are included in a plane located at a distance R from the rotation axis. Each pivot axis is offset by a value d, toward the exterior of the spring, with respect to the planar face of the corresponding seat.
Although this technology yields good results at moderate or average speeds, it has nevertheless been found that it did not allow operating problems at high output, such as ejection of the seats from their receptacles and/or impacts with said receptacles, to be solved